Photocorrosion and Film Formation of Ga(As, P) Electrodes Photoelectrochemical and Surface Physical Studies

A set of low n-doped GaAsl_yP ~ epitaxial layers, with the composition y in the range 0-< y-< 0.75, were prepared by metal organic hemical vapor deposition (MO-CVD) on n § substrate. The samples were mounted as rotating ring-disk elec-trodes, and studied by photoelectrochemical and surface physical techniques. In one type of experiments, the quantum conversion efficiency ~ (at one selected wavelength) and the stability S towards photocorrosion i K4Fe(CN)6 solutions were measured for a prolonged time (100 min). The experiments revealed the effect of pretreatment (polishing, etching) of the electrode. A thin film was formed on the surface, improving/~he stability but also slightly impairing the efficiency. Using energy dispersion analysis of x-rays (EDAX), secondary ion mass spectroscopy (SIMS), and IR reflection spectro-scopy it was established that the film consists of an analogue of A1 containing Prussian blue. Increasing the KC1 concen-tration of the electrolyte l d to an improvement ofS. Photoelectrochemistry (PEC), first studied purely for its scientific interest (1), gained momentum during the 1970's as a possible means of conversion and storage of solar energy (2). In recent years it has been realized that PEC techniques can be useful for other practical applications a